Relação entre o modo meridional de TSM no Pacífico e o ENOS e seus efeitos sobre a precipitação na Amazônia

Abstract

In this study we aim to caracterize the Pacific Meridional Mode (PMM) of Sea Surface Temperature (SST) and its relationship with El Niño-Southern Oscillation (ENSO) and the rainfall in the Amazonic region during 1901 to 2010. The methodology of this study is based on the method of Combined and Extended Empirical Orthogonal Function (CEOF and EEOF respectively) to identify the spatial and temporal patterns of the PMM. Composite analyses and linear correlation tools are used to search for the relations between the PMM, ENSO and precipitation. The results show that the spatial pattern of PMM presents a variability of 8 years and is best defined in the months of June through August (JJA). Correlations between the timeseries associated with PMM and precipitation show a temporal dependency, with a change of pattern after the 1980s. The effects combined of ENSO and PMM on the precipitation over Tropical South America were also investigated. In this case, the results suggest that the ocurrence of positive or negative PMM patterns during the initial phase of ENSO events can act in the sense of configurating the positioning of the maximum anomaly centers associated with ENSO and as as consequence alter the pattern of precipitation over the Amazon. On the other hand, ENSO in its decaying phase doesn’t seem to interfere in the development of PMM and its relation with rainfall.